Heater



Feb 1946- H. J. DE N. MCCOLLUM 2,395,418

HEATER Filed July 16, 1943 2 Sheets-Sheet 1 Feb. 26, 1946.

HEATER Filed July 16, 1943 2 Sheets-Sheet 2 ,the ventilating air in Patented Feb. 26, E94

PATENT OFFICE HEATER Henry J. De N. McCollum,

McCollum executrix of McCollum, deceased Application July 16,

8 Claims.

This application relates to heaters, and particularly to heaters of the internal combustion type. The primary object of the present invention is teristics of the heater will be improved.

Other objects and advantages of the invention will become apparent during the description, reference being had to the drawings, in which:

Fig. 1 is a vertical sectional view taken longitudinally through an internal combustion heater;

Fig. 2 is-a cross-sectional view taken on the line Fig. 3 is an enlarged cross-sectional view taken on the line 33 of Fig. 1; and

Figs, 4; and 5 are sectional views taken on the lines fl-l and 55, respectively, of Fig. 3.

The drawings illustrate a heater or the internal combustion type. As shown in Fig. 1, particularly by the how arrows, air for both ventilating and combustion purposes enters the heater through an inlet fitting H. The air may be forced through the heater by blower, or the like. an annular passage it of the heater and Part of the air flows through 14 formed-between the shell the outer surface of a generally tubular heat exchanger l8 having a plurality of fins 2t. The air, which has been heated during its iiow through passage M, then flows through an outlet fitting 22 to the space which is to be heated, as, for example, the cabin of an airplane.

Part or the air flows through centrally located I aligned tubes 2t and 25 and through a curved end fitting 23 into a return tube 30, which is outside the heat exchanger shell, to a carburetor 32. In the carburetor the air is mixed with fuel supplied by a conduit 3 3, and the combustible mixture thus formed :fiows through an induction tube 36 into the combustion chamber 38.

The products of combustion leaving the combustion chamber flow along the inside of the heat exchanger it, giving up heat through the wall and fins of the heat exchanger to the ventilating air flowing in passage it.

sure therein somewhat lower than the pressure of passage it and at outlet 22. Means to dampen the vibrations resulting from combustion are provided inside the heat ex-' changer comprising a mufiier shell plurality of small openings 42, and stamped ends and it. If preferred, the mufiler casing instead of being left substantially empty, as shown,

means of a ram or Chicago, Ill.; Thelma said Henry J. De N.

1943, Serial No. 494,942

may be filled with an acoustic damping material,

such as stainless steel wool or glass wool.

The combustion chamber 38 may be formed by a cylindrical stamping 5|] having an interned end 5 forming a rear secured to a supporting ring 53 which is welded to the end of the heat exchanger and which is itself supported by means of brackets 55 secured to the shell I 6. The tube 24 extends through the center of the stamping 50, causing the combustion chamber to have an annular form.

As shown in Fig. 3, the induction tube 36 enters the combustion chamber 38 at the side and near the bottom of the chamber, and the end of the tube is curved upwardly closely adjacent the wall of the combustion chamber. Thus, the combustible mixture as it leaves the induction tube is flowing upwardly and substantially tangentially to the wall of the combustion chamber. The outer cylindricalsurface of the wall gives the combustible mixture a, generally circular motion,

and the velocity of the combustible mixturetends to make it adhere closely to the wall of the chamber as it flows to the opposite side of the chamber 25 to be ignited. As seen in Fig. 1, the upwardly curved end of the induction tube in the combustion chamber, is also slightly inclined toward the rear of the chamber to facilitate complete combustion and to insure maximum combustion within the chamber.

The induction tube has a relatively large cross section, permitting a large amount of combustible mixture to flow to the combustion chamber and causing the pressure drop in the combustion chamber below the supply pressure of the combustible mixture to be relatively slight. Thus a. large amount of the combustible mixture may be brought to the combustion chamber during a given period at a relatively low velocity.

In its flow along the wall of the combustion chamber, the combustible mixture is confined between the rear of the chamber and the radially inwardly extending flange 51 of an annular stamping 54 secured to the wall of the combustion chamber.

The igniter is positioned in a pocket outside the annular combustion chamber in order that it will not be exposed directly to cooling by the incoming combustible mixture and in order that the free flow and full combustion of the mixture will not be impeded by an obstruction inside the combustion chamber.

A housing 56, forming a pocket for the igniter, is secured to the outer cylindrical surface of the annular stamping 50. A casing 58, having an wall and having a radial flange 52 igniter of the hot wire type therein, is screwed in the top of housing 56 and extends downwardly into the hollow central portion thereof. Inside the stem 60 of the casing 58 is the coil 62 which 68, and a substantial portion of the mixture will be diverted into the slot.

As seen clearly in Fig. 3, the slot 68 slants downwardly from the combustion chamber toward the igniter'po'cket, in order that the combustible mixture may fiow continuously downward from the side wall of the combustion chamber, and thus cannot accumulate or stagnate in the slot at the top of the igniter pocket.

In order to further contrbl the flow of the combustible mixture, and to direct a greater portion thereof into contact with the igniter, a rib I extending axially of the combustion chamber and secured to the wall thereof serves as a dam to cause a greater flow of combustible mixture through slot 68. The rib may extend either partially or wholly across the side wall of the combustion chamber. It must of course be placed below slot 68 and above slot '13 which opens into an outlet passage 12 through which the ignited mixture flows from the ignition pocket back to the combustion chamber. The position of the rib relative to the upper and lower slots may be varied, but a position about midway between the.

two has been found very satisfactory. The rib 10 is preferably of a relatively slight height, in order not to interfere with flow of the burning gases in the combustion chamber. The richest mixture of the entering fuel tends to follow the wall of the combustion chamber, and it is therefore possible for a relatively low rib to divert sufflcient fuel to the igniter pocket to accomplish theheater starting operation.

' In order to ignite the gases in the combustion chamber if they should cease burning due to some extraneous factor, after having'once been ignited, a re-igniter 14 of the coil type is provided, the coil being mounted in a member which is screwed into a fitting 16 secured to the outside of the stamping 50.

When it is desired initially to ignite the combustible mixture in the combustion chamber of the heater, the electric circuit igniter coil 62 is closed by means of a manually operable switch (not shown), and the wire 62 is thereby brought to an extremely high temperature sufficient to cause combustion of the mixture supplied by the induction tube 36. Said mixture flows along the wall of the combustion chamber between the rear of the chamber and the radial flange of ring 54. As it passes the slot 68 a substantial portion is diverted into the igniter pocket 66 where it comes into contact with the heated wire and is ignited, passing then through passage 12 back to the combustion chamber where it aids in igniting the rest of the combustible mixture. The flow of combustible mixture into slot 68 is augmented by the effect of the rib l0.

With the arrangement described it is possible to start the heater rapidly and efllciently even though the surrounding temperature is extremely low, and even thoughthe flow rate of the combustible mixture to the combustion chamber is relatively low. It has' been found that, with the arrangement shown, the burner will ignite without difficulty at a temperature well below 60 F., and that a relatively large mixture induction tube may be used without making the starting of the burner diflicult. It is therefore possible to increase the B. t. u. output of the heater and to operate satisfactorily with a lower pressure differential between the intake and exhaust sides of the heater.

Although a particular embodiment of my invention has been described, it will be understood by those skilled in the art that the object of the invention may be attained by the use of con-' structions different in certain respects from that disclosed without departing from the underlying principles of the invention. I therefore desire by the following claims to include within the scope of my invention all such variations and modifications by which substantially the results of my invention may be obtained through the bustion chamber at one side thereof, and an.

igniter for said combustible mixture positioned in said pocket, in combination, means confining the flow of combustible mixture along the chamber wall to the space adjacent to the point at which the mixture is introduced, the wall of the combustion chamber having a slot therein permitting communication of the chamber with the igniter pocket, said slot extending across the path of flow of the combustible mixture for substantially the entire space to which that flow is confined, and a rib projecting inwardly froni' the surface of the combustion chamber wall alongside of said slot and extending across the path of flow of the combustible mixture and serving as a dam to increase flow of combustible mixture through the slot.

2. In an internal combustion heater having a combustion chamber with a substantially cylindrical outer wall, means for introducing a combustible mixture into said chamber substantially tangentially thereof, means providing a pocket beyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, in combination, means confining the flow of combustible mixture along the chamber wall to the space adjacent to the point at which the mixture is introduced, an axiall extending slot in the wall of the combustion chamber permitting communication of the chamber with the igniter pocket, said slot extending across the path of flow of the combustible mixture for substantially the entire space to which that flow is confined, and an axially extending rib projecting inwardly from the surface of the combustion chamber wall and extending across the path of flow of the combustible mixture, said rib being positioned posteriorly of the slot and serving as a dam to increase flow of combustible mixture through the slot.

3. In an internal combustion heater having a combustion chamber, means for introducing a combustible mixture into said chamber, means providing a pocket beyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, in combination, means confining the flow of combustible mixture along the chamber wall to the space opposite'to the point at which said pocket is located, a slot in the wall of the combustion chamber permitting communication of the chamber with the igniter pocket, and a rib projecting inwardly from the surface of the combustion chamber wall alongside of said slot and extending across the path of flow of the combustible mixture and serving as a dam to increase flow of combustible mixture through the slot.

4. In an internal combustion heater having a. combustion chamber, means for introducing a combustible mixture into said chamber, means providing a pocket b'eyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, a slot in the wall of the combustion chamber permitting communication of the chamber with the igniter pocket, and a rib projecting inwardly from the surface of the combustion chamber wall adjacent to said slot and substantially parallel therewith and extending across the path of flow of the combustible mixture and serving as a dam to increase flow of combustible mixture through the slot.

5. In an internal combustion heater having a combustion chamber, means for introducing a of combustible mixture through the inlet conneccombustible mixture into said chamber, means providing a pocket beyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, said pocket havinginlet and outlet connections to said chamber by means of two slots in the wall of the chamber, a rib projecting inwardly from the surface of the combustion chamber wall positioned between said two slots and substantially parallel with the inlet slot and extending across the path of flow of the combustible mixture to serve as a dam increasing the flow of combustible mixture through the inlet slot of the igniter pocket.

6. In an internal combustion heater having a combustion chamber with a substantially cylindrical outer wall; means for introducing a combustible mixture into said chamber substantially tangentially thereof, means providing a pocket beyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, said pocket having spaced inlet and outlet connections 0 providing a pocket beyond the wall of said corn tion.

7. In an internal combustion heater having a combustion chamber with a substantially cylindrical outer wall, means for introducing a combustible mixture into said chamber substantially tangentially thereof, means providing a pocket ,beyond the wall of said combustion chamber at one side thereof, and an igniter for said combustible mixture positioned in said pocket, in combination, means axially confining the flow of combustible mixture along the chamber wall to the space adjacent to the point at which'the mixture is introduced, an axially extending slot in the wall of the combustion chamber serving as an inlet connection for the igniter pocket, said slot extending across the path of flow of the combustible mixture for substantially the entire space to which that flow is confined, an axially extending rib projecting inwardly from the surface of the combustion chamber wall and extending across the path of flow of the combustion mixture, said rib being positioned. posteriorly of the inlet slot and serving as a dam to increase the flow of combustible mixture therethrough, and a second slot in the wall of the combustion chamber serving as an outlet for the igniter pocket and positioned on the opposite side of said rib from th inlet slot,

8. In an internal combustion heater having a combustion chamber, means for introducing a combustible mixture into said chamber, means bustion chamber at one side thereof, anigniter for said combustible mixture positioned in said pocket, a slot opening from the combustionchamber and extending outwardly and downwardly into said pocket providing communication between the chamber and the pocket, and a rib projecting combustible mixture through the slot into the pocket.

HENRY J. DE N. McCOLLUM. 

